/*
 * Copyright 2002-2016 the original author or authors.
 *
 * Licensed under the Apache License, Version 2.0 (the "License");
 * you may not use this file except in compliance with the License.
 * You may obtain a copy of the License at
 *
 *      https://www.apache.org/licenses/LICENSE-2.0
 *
 * Unless required by applicable law or agreed to in writing, software
 * distributed under the License is distributed on an "AS IS" BASIS,
 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 * See the License for the specific language governing permissions and
 * limitations under the License.
 */

package com.hqd.ch03.v42.web.context.request;


import com.hqd.ch03.v42.core.NamedInheritableThreadLocal;
import com.hqd.ch03.v42.thread.NamedThreadLocal;

public abstract class RequestContextHolder {


    private static final ThreadLocal<RequestAttributes> requestAttributesHolder =
            new NamedThreadLocal<>("Request attributes");

    private static final ThreadLocal<RequestAttributes> inheritableRequestAttributesHolder =
            new NamedInheritableThreadLocal<>("Request context");


    /**
     * Reset the RequestAttributes for the current thread.
     */
    public static void resetRequestAttributes() {
        requestAttributesHolder.remove();
        inheritableRequestAttributesHolder.remove();
    }

    /**
     * Bind the given RequestAttributes to the current thread.
     *
     * @param attributes  the RequestAttributes to expose,
     *                    or {@code null} to reset the thread-bound context
     * @param inheritable whether to expose the RequestAttributes as inheritable
     *                    for child threads (using an {@link InheritableThreadLocal})
     */
    public static void setRequestAttributes(RequestAttributes attributes, boolean inheritable) {
        if (attributes == null) {
            resetRequestAttributes();
        } else {
            if (inheritable) {
                inheritableRequestAttributesHolder.set(attributes);
                requestAttributesHolder.remove();
            } else {
                requestAttributesHolder.set(attributes);
                inheritableRequestAttributesHolder.remove();
            }
        }
    }

    /**
     * Return the RequestAttributes currently bound to the thread.
     *
     * @return the RequestAttributes currently bound to the thread,
     * or {@code null} if none bound
     */

    public static RequestAttributes getRequestAttributes() {
        RequestAttributes attributes = requestAttributesHolder.get();
        if (attributes == null) {
            attributes = inheritableRequestAttributesHolder.get();
        }
        return attributes;
    }

    public static void setRequestAttributes(RequestAttributes attributes) {
        setRequestAttributes(attributes, false);
    }

    public static RequestAttributes currentRequestAttributes() throws IllegalStateException {
        RequestAttributes attributes = getRequestAttributes();
        if (attributes == null) {
            throw new IllegalStateException("No thread-bound request found: " +
                    "Are you referring to request attributes outside of an actual web request, " +
                    "or processing a request outside of the originally receiving thread? " +
                    "If you are actually operating within a web request and still receive this message, " +
                    "your code is probably running outside of DispatcherServlet: " +
                    "In this case, use RequestContextListener or RequestContextFilter to expose the current request.");
        }
        return attributes;
    }


}
